let make a car specific thread(dsmers)
I don't think I've ever used one, a long flat head usually does the trick. Just don't yank too hard down on the tensioner pulley. The hydraulic tensioner adjusts accordingly.
The purpose of the tensioner is to put tension on the belt, NOT to pick up slack and adjust for install error. If you are not properly setting the belt tension then that is the answer to the timing belt problems about 30 pages back.
I was going to go by the vfaq article, that way I wouldn't need to remove the belt http://www.vfaq.com/index-main.html








not my install, but none the less you are right.